Bristly sponges (Calcarea) are a group of sponges in which the skeleton is composed of spicules of calcium carbonate which typically gives them a bristly surface.

Sponges (Phylum Porifera) are a group of very primitive multicellular aquatic animals numbering about five thousand species. Sponges are such primitive animals that biologists originally believed they were plants. Most members of this family of invertebrates are marine species. The light, fibrous, flexible and absorbent skeleton of certain species have been popularly used for cleaning and bathing. Although some natural sponges are still marketed today, most used today are synthetically made. The four known classes of sponges are:

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.